1. Field of the Invention
The present invention relates to a power supply of an electrical apparatus, and more particularly, to a power supply employing a standby power converter for use in a standby mode of an electrical apparatus.
2. Discussion of the Related Art
Since a typical electrical apparatus operates on an AC power source but internally requires at least one DC power supply, the apparatus requires internal means for AC to DC conversion. Meanwhile, for saving energy, the same apparatus is provided with a standby mode, allowing continuous operation with minimum power consumption, in addition to a normal operational mode for its normal functions. During the standby mode, which is typically initiated by detecting a predetermined period of non-use, a microcomputer is supplied with minimum power to output a control signal for controlling the system while enabling a revival of the system's normal functions as desired. Accordingly, a voltage regulator is generally employed to output a regulated voltage during normal operation as well as during the standby mode, thus providing both normal operating power and standby mode power to the microcomputer.
FIG. 1 illustrates a power supply according to a related art, for use in an electrical apparatus as described above.
Referring to FIG. 1, a power supply of an electrical apparatus according to a related art is comprised of a DC power supply 10 for outputting a DC voltage converted from a commercial AC voltage source; a voltage regulator 20 for outputting a regulated voltage; a microcomputer 30, receiving the regulated voltage, for outputting a mode control signal according to the operational mode of the electrical apparatus, i.e., normal and standby; and a power converter 40, controlled by the mode control signal, for converting a received DC voltage into a plurality of operation voltages, for example, 5V and 12V, required for powering a plurality of loads 50 and 60.
In the operation of the above power supply, the DC power supply 10 outputs a DC voltage to the voltage regulator 20 and power converter 30, and the voltage regulator supplies a regulated voltage to the microcomputer 30, which uses the regulated voltage as its main power for outputting the mode control signal to the power converter 40. The main power requires regulation due to its simultaneous use for the overall operation of the power supply as well as other components of the electrical apparatus. In a normal operational mode, the mode control signal of the microcomputer 30 enables the power converter 40 to supply respective DC voltage outputs to the loads 50 and 60, but in standby mode, the mode control signal turns off the power converter, which cuts off the DC voltage outputs to one or more of the loads.
It should be noted that, as described above, the voltage regulator 20 is capable of supplying a regulated DC voltage having sufficient current to operate numerous components in the normal mode. Furthermore, since voltage regulation is inherently wasteful, the voltage regulator 20 operates at a low efficiency and is especially inefficient in the standby mode. Therefore, the power supply according to the related art, which uses the voltage regulator for the microcomputer's main power during standby mode, consumes excessive power even when operating in the standby mode.